Quicktime File Format (2012-08-14).pdf

Media Data Atom TypesHint Sample Data FormatAdditional data tableA table of variable length containing additional information. Additional information is formatted as aseries of tagged entries.This field always contains a tagged entry indicating the RTP time scale for RTP data. All other taggedentries are optional.Three data tags are currently defined for RTP data. One tag is defined for use with any type of data. Youcan create additional tags. Tags are identified using four-character codes. Tags using all lowercase lettersare reserved by Apple. Ignore any tagged data you do not understand.Table entries are structured like atoms. The structure of table entries is shown in Table 4-19 (page 258).Table 4-19The structure of table entriesFieldEntry lengthData tagDataFormat32-bit integer4-char codeVariableBytes44Entry length - 8Tagged entries for the 'rtp ' data format are defined as follows:'tims'A 32-bit integer specifying the RTP time scale. This entry is required for RTP data.'tsro'A 32-bit integer specifying the offset to add to the stored time stamp when sending RTP packets. If thisentry is not present, a random offset should be used, as specified by the IETF. If this entry is 0, use anoffset of 0 (no offset).'snro'A 32-bit integer specifying the offset to add to the sequence number when sending RTP packets. If thisentry is not present, a random offset should be used, as specified by the IETF. If this entry is 0, use anoffset of 0 (no offset).2012-08-14 | © 2004, 2012 Apple Inc. All Rights Reserved.258